(LEAD) Dongdaemun Gate briefly set on fire in apparent arson

(ATTN: CORRECTS detail in 3rd para; ADDS more info about suspect's statement in 2nd to last para)

SEOUL, March 9 (Yonhap) -- Dongdaemun Gate, a heritage site in central Seoul, was briefly set on fire in an apparent arson attack, police said Friday.

The fire in Heunginjimun, the gate's official name, was first reported at around 2 a.m., firefighters said. A witness reported seeing smoke coming out of the wall.

The fire was put out in four minutes, causing soot on part of its wall with no serious damage or human casualties. Dongdaemun Gate is South Korea's Treasure No. 1.

Police apprehended a 43-year-old suspect on site, identified only by his surname Chang. He did not appear to be intoxicated at the time of the apprehension, they added. He is undergoing questioning.

Police believe the suspect illegally entered the fortress and lit the fire on a pile of paper boxes using a lighter in frustration out of personal grievances. He reportedly told police that he was angry he was denied an insurance claim for a traffic accident.

They said they are working to determine his motive.

This photo shows an east-side entrance of Dongdaemun Gate in Seoul on March 9, 2018. Authorities cordoned off the area with tape after an apparent arson caused light damage. (Yonhap)